* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    background: linear-gradient(to bottom, #f9fafb 0%, #ffffff 100%);
    font-family: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    color: #1f2937;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
    padding: 0;
}

main {
    width: 100%;
    max-width: 800px;
    height: 100vh;
    display: flex;
    flex-direction: column;
    background-color: transparent;
}

#history {
    flex: 1;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    padding: 32px 24px 120px 24px;
    scroll-behavior: smooth;
}

#inputArea {
    position: fixed;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 100%;
    max-width: 800px;
    padding: 0 24px 24px 24px;
    background: linear-gradient(to top, rgba(255,255,255,0.98) 0%, rgba(255,255,255,0.95) 70%, transparent 100%);
    backdrop-filter: blur(8px);
    pointer-events: none;
}

#form {
    display: flex;
    gap: 10px;
    background-color: #ffffff;
    padding: 12px 16px;
    border-radius: 24px;
    border: 1px solid #e5e7eb;
    transition: all 0.2s ease;
    align-items: center;
    box-shadow: 0 2px 8px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
    pointer-events: all;
}

#form:focus-within {
    border-color: #3b82f6;
    box-shadow: 0 4px 12px rgba(59,130,246,0.12), 0 2px 4px rgba(59,130,246,0.08);
}

#userInput {
    flex: 1;
    border: none;
    background: transparent;
    padding: 8px 4px;
    font-size: 15px;
    outline: none;
    color: #111827;
    min-width: 0;
    font-family: inherit;
}

#userInput::placeholder {
    color: #9ca3af;
}

#sendMessage {
    background: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
    color: white;
    border: none;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
    flex-shrink: 0;
    box-shadow: 0 1px 3px rgba(59,130,246,0.3);
}

#sendMessage:hover:not(:disabled) {
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    transform: scale(1.05);
    box-shadow: 0 2px 6px rgba(59,130,246,0.4);
}

#sendMessage:active:not(:disabled) {
    transform: scale(0.98);
}

.userQuestionDiv {
    background: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
    color: white;
    max-width: 75%;
    padding: 14px 18px;
    border-radius: 20px 20px 4px 20px;
    align-self: flex-end;
    font-size: 15px;
    line-height: 1.5;
    word-break: break-word;
    box-shadow: 0 1px 2px rgba(0,0,0,0.08);
}

.aiResponseDiv {
    background-color: #f9fafb;
    color: #1f2937;
    max-width: 75%;
    padding: 14px 18px;
    border-radius: 20px 20px 20px 4px;
    align-self: flex-start;
    border: 1px solid #e5e7eb;
    font-size: 15px;
    line-height: 1.6;
    word-break: break-word;
    box-shadow: 0 1px 2px rgba(0,0,0,0.04);
}

.questionDiv {
    font-size: 15px;
    font-weight: 600;
    color: #3b82f6;
    margin-bottom: 8px;
}

.answerDiv {
    font-size: 15px;
    line-height: 1.6;
    color: #374151;
}

/* Scrollbar styling */
#history::-webkit-scrollbar {
    width: 8px;
}

#history::-webkit-scrollbar-track {
    background: transparent;
}

#history::-webkit-scrollbar-thumb {
    background: rgba(156, 163, 175, 0.3);
    border-radius: 10px;
    border: 2px solid transparent;
    background-clip: padding-box;
}

#history::-webkit-scrollbar-thumb:hover {
    background: rgba(156, 163, 175, 0.5);
    background-clip: padding-box;
}

/* Mobile responsive */
@media (max-width: 768px) {
    body {
        padding: 0;
    }

    main {
        max-width: 100%;
    }

    #history {
        padding: 20px 16px 100px 16px;
        gap: 1.25rem;
    }

    #inputArea {
        max-width: 100%;
        padding: 0 16px 16px 16px;
    }

    #form {
        padding: 10px 12px;
        gap: 8px;
        border-radius: 20px;
    }

    #userInput {
        padding: 6px 4px;
        font-size: 16px;
    }

    #sendMessage {
        width: 34px;
        height: 34px;
    }

    .userQuestionDiv,
    .aiResponseDiv {
        max-width: 85%;
        padding: 12px 16px;
        border-radius: 18px 18px 4px 18px;
        font-size: 15px;
    }

    .aiResponseDiv {
        border-radius: 18px 18px 18px 4px;
    }

    .questionDiv {
        font-size: 15px;
        margin-bottom: 6px;
    }

    .answerDiv {
        font-size: 15px;
    }
}

#header {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

#use-btn {
    position: fixed;
    top: 16px;
    left: 16px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    border: 1px solid #d1d5db;
    background-color: #ffffff;
    color: #1f2937;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 8px 24px rgba(17, 24, 39, 0.1);
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease, color 0.2s ease;
    z-index: 80;
}

#use-btn:hover {
    transform: scale(1.03);
    box-shadow: 0 10px 28px rgba(17, 24, 39, 0.14);
    border-color: #3b82f6;
    color: #3b82f6;
}

#use-btn:focus-visible {
    outline: 2px solid #3b82f6;
    outline-offset: 2px;
}

#icon {
    width: 22px;
    height: 22px;
    border-radius: 50%;
    pointer-events: none;
}

.help-popup {
    position: fixed;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 24px;
    background-color: rgba(15, 23, 42, 0.36);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity 0.24s ease, visibility 0.24s ease;
    z-index: 120;
}

.help-popup.is-open {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.help-popup-panel {
    width: min(680px, 100%);
    max-height: min(80vh, 720px);
    overflow: auto;
    background-color: #ffffff;
    border: 1px solid #e5e7eb;
    border-radius: 20px;
    padding: 28px;
    box-shadow: 0 20px 48px rgba(17, 24, 39, 0.22);
    color: #1f2937;
    transform: translateY(8px) scale(0.985);
    transition: transform 0.24s ease;
}

.help-popup.is-open .help-popup-panel {
    transform: translateY(0) scale(1);
}

.help-popup-panel h2 {
    font-size: 1.4rem;
    margin-bottom: 10px;
}

.help-popup-panel h3 {
    font-size: 1rem;
    margin-top: 18px;
    margin-bottom: 8px;
    color: #111827;
}

.help-popup-panel p,
.help-popup-panel li {
    font-size: 0.95rem;
    line-height: 1.65;
    color: #374151;
}

.help-popup-panel ol {
    padding-left: 1.1rem;
}

.help-popup-panel code {
    background-color: #f3f4f6;
    border-radius: 6px;
    padding: 0 6px;
    color: #1f2937;
}

.help-note {
    margin-top: 14px;
    border-left: 3px solid #3b82f6;
    padding-left: 10px;
}

.help-close-btn {
    position: relative;
    margin-left: auto;
    display: block;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid #d1d5db;
    background-color: #ffffff;
    color: #374151;
    cursor: pointer;
    font-size: 0.8rem;
    font-weight: 600;
    transition: transform 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.help-close-btn svg {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);

    transition: 0.3s ease;
}

.help-close-btn:hover {
    transform: scale(1.05);
    color: #3b82f6;
    border-color: #3b82f6;
}

.help-close-btn:focus-visible {
    outline: 2px solid #3b82f6;
    outline-offset: 2px;
}

#closePopUp-icon {
    transition: 0.3s ease;
}

#closePopUp-icon-hover {
    opacity: 0;
}

.help-close-btn:hover #closePopUp-icon {
    opacity: 0;
}

.help-close-btn:hover #closePopUp-icon-hover {
    opacity: 1;
}

@media (max-width: 600px) {
    .help-popup {
        padding: 14px;
    }

    .help-popup-panel {
        border-radius: 16px;
        padding: 18px;
    }

    #use-btn {
        width: 44px;
        height: 44px;
        top: 12px;
        left: 12px;
    }
}